In my forthcoming book, “Scarlet Letters: The Ever-Increasing Intolerance of the Cult of Liberalism Exposed,” I address the emergence of what I call “progressive neo-puritanism.”

With the exception of Islam, an unlikely ally in the rainbow coalition, this may well be the most judgmental, vengeful, unforgiving quasi-religious cult in the Western world today.

In the past week, the good citizens of Indiana got branded with a scarlet H by the most judgmental and vengeful of all the neo-puritan sub-cults, the gay rights sect.

Oregon’s Melissa and Aaron Klein understood full well what Indiana lawmakers were hoping to accomplish. The couple used to operate a storefront bakeshop, Sweet Cakes by Melissa, in metropolitan Portland.

In February 2013, these Christian parents of five refused to bake a wedding cake for a lesbian couple. The lesbians promptly filed a civil rights complaint against the Kleins, and their supporters set out to cripple their business.

Their tactics included death threats, vandalizing the bakery’s vehicle on several occasions, and the intimidation of the clients and vendors listed on the shop’s website.

“They have an odd way of showing tolerance,” quipped Aaron of his local neo-puritans. Overwhelmed, the Kleins moved their business home but were unable to list their phone number due to the constant harassment.

With the clientele whittled down to family and friends, the 35-year-old Aaron took a job driving a garbage truck to support the family.

The Huffington Post reported the business closure with unusual restraint, a virtue not all its proudly and hysterically anti-Christian readers shared. What follow is a sample right off the top:

If the practice of your faith hinges on the degradation and humiliation of God’s creations, might I suggest you’ve missed the mark entirely?

Allowing discrimination is not freedom of religion, it’s bigotry.

The constant self-victimization of religious zealots has become quite tedious.

Their religion is really a metaphor for “I’m a bigot and I hate gays and lesbians.”

So basically what they said is “We find homosexuals disgusting and we refuse to serve them, but it’s not discrimination because our religion says it’s OK.”

We don’t serve your kind here, because in our holy book, GAWD said “thou shalt not bake cakes for people like that.”

Wouldn’t a religious exemption from anti-discrimination laws have been nice for every bigot?

Of course, the Kleins never expressed any hatred of gays and never refused any gay person service. They simply refused to bake a cake honoring a practice contrary to their faith.

“Wanna discriminate against somebody based on your religion?” wrote one aspiring Torquemada. “Be prepared to be investigated, fined, and potentially shut down.”

At the time of this writing, the Kleins are facing a $150,000 fine, not easily paid on a garbage man’s salary.

The neo-puritans of Colorado proved no more tolerant. Jack Phillips had been making wedding cakes at his suburban Denver store, Masterpiece Cakeshop, for nearly 20 years when his life took a turn for the absurd.

A devout Christian, Phillips welcomed all comers to his shop, but as a rule he declined to make his custom-designed “masterpieces” for events that conflicted with his faith, Halloween included.

In July 2012 two men came to his shop wanting a cake to celebrate their same-sex wedding. Phillips politely explained he would make any other kind of baked goods they might want but not a wedding cake.

Besides, he noted, Colorado did not recognize same-sex marriages. The easily offended couple promptly rushed to the Colorado Division of Civil Rights.

“Being discriminated against is a form of personal invalidation,” one of the husbands-to-be told the media. “It’s being degraded and put on a lower level than other people in society.”

Why gay couples continually allowed themselves to be “degraded” by the rare Christian refusenik seems odd only to those who presume their intentions to be innocent. They rarely are.

When the case went public, Nicolle Martin, Phillips’ “recovering liberal” attorney, thought reason would prevail. “I was a little naïve,” she confessed. “I have come full circle to realize that if you conflict with prevailing liberal orthodoxy, they will root you out. They will find you.”

The Colorado Division of Civil Rights ordered Phillips to “cease and desist” from discriminating against same-sex couples. When Phillips appealed, the Colorado Civil Rights Commission upheld the original decision and then some.

The chairwoman of the Colorado Civil Rights Commission, an attorney named Katina Banks, signed the damning decree. Unmentioned in the reporting was that a year earlier Banks and her female sweetheart posted the story of their relationship on a “freedom to marry” site.

“We want to be married to express our love and commitment,” Banks lamented, “and we could do that if we went somewhere else where it’s allowed – but it would have no meaning here where we live.”

They lived in the same place at the same time as the gay couple demanding a cake from Phillips. How, Phillips wondered, was he to educate his staff in an act that had “no meaning” in Colorado?

The Commission’s Orwellian edict caused just enough unease among liberals that more than a few felt obliged to rationalize it. “This is what [Phillips] should have done originally,” argued one respondent on the Huffington Post. “Not make wedding cakes a part of his business.”

In other words, when Phillips started his cake-making business in 1994, two years before President Bill Clinton signed the Defense of Marriage Act into law, he should have anticipated this 180-degree turn in the party line and launched a cake business that did not include wedding cakes.

Those on the soft right who think they can placate neo-puritans by sacrificing the occasional cake maker do not understand the movement.

The switch from “liberal” to “progressive” mirrors a political reality. At the risk of tautology, progressives “progress.”

If old-school liberals could content themselves with a fixed set of principles, progressives, like sharks, have to move forward.

Their identity depends on it. And, for them, our freedoms are just so much chum.